Multipurpose machine for bending metal tubes, both small and large

ABSTRACT

Machine for bending pieces of elongated form, both to the right and to the left, and of any transverse size and thickness compatibly with the maximum mechanical torque exertable by the machine itself, including a base, an upper surface on which all the mechanisms are mounted which allow bending the piece, as well as, within the base, the power unit which provide the necessary torque and power. The mechanisms include kits removably mounted on the machine and adaptable to the shape and size of the respective piece. An overturnable and rotatable member at one end bears a counter-matrix substitutable for small tubes and at the other end bears a counter-matrix substitutable for large tubes. The member allows selectively moving a matrix closer to the corresponding counter-matrix and bending the tube both to the right and to the left, according to which side of the overturnable member is momentarily directed upward.

FIELD OF THE ART

The present invention refers to the field of machines for bending metal tubes.

PRIOR ART

Machines of this type have already been known for a long time. Nevertheless, substantial improvements to this machine tool type have occurred over time and in particular the same inventor of the present patent application has recently made essential improvements, which are contained in various Italian patent applications by the same Applicant of the present application, including for example the following (some of these have also been extended as PCT international applications with the relative Italian priorities): RM2012A000620, relative to a “Counter-matrix with inserts, for metal tube bending machines”, RM2012A000618 which regards a “Modular machine, for bending metal tubes”, RM2014A000160 regarding a “Controlled system for retreating the counter-matrix in a tube-bending machine operating without internal core”, to only mention a few.

As seen, the respective improvements have each regarded one particular aspect, even if essential, of the metal tube-bending machine with matrix and counter-matrix, operating without internal core.

Nevertheless, a fundamental problem has not yet been resolved. There are machines that bend the metal tube both to the right and to the left, or which comprise particular substitutable inserts of the counter-matrix (abovementioned application RM2012A000620), but no one has yet thought to provide a machine capable of bending both to the right and to the left and simultaneously bending tubes over a wide range of diameters and thicknesses. Therefore, the object of the present invention consists of providing a multipurpose tube-bending machine capable of bending tubes both to the right and to the left and simultaneously over a wide range of values of diameter and thickness of the metal tube. In this manner, the client who purchases one such machine will no longer be obliged to purchase two, or even multiple machines, to do the same thing that only one machine—i.e. that of the present invention—is capable of doing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be illustrated with reference to a preferred but non-limiting embodiment, shown in the enclosed drawings:

FIG. 1 shows the plan view of the tube-bending machine according to the preferred embodiment of the present invention, in a first initial position of the double-rotation (“double-twist”) member, for bending metal small tubes (i.e. with small diameter) to the right;

FIG. 2 shows a view analogous to the preceding FIG. 1, during the operation of bending to the right the small-diameter tube;

FIG. 3 shows the plan view of the tube-bending machine according to the preferred embodiment of the present invention, in a second initial position of the double-rotation (“double-twist”) member, for bending metal large tubes (i.e. with large diameter) to the left;

FIG. 4 shows a view analogous to the preceding FIG. 3, during the operation of bending to the left the large-diameter tube;

FIG. 5 shows the plan view of the tube-bending machine according to the preferred embodiment of the present invention, in a third initial position of the double-rotation (“double-twist”) member, for bending metal large tubes (i.e. with large diameter) to the right;

FIG. 6 shows a view analogous to the preceding FIG. 5, during the operation of bending to the right the large-diameter tube;

FIG. 7 shows the plan view of the tube-bending machine according to the preferred embodiment of the present invention, in a fourth initial position of the double-rotation (“double-twist”) member, for bending metal small tubes (i.e. with small diameter) to the left;

FIG. 8 shows a view analogous to the preceding FIG. 7, during the operation of bending to the left the small-diameter tube.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

The machine of the present invention is of the type generally already known to the man skilled in the art, i.e. that operating with a matrix and a counter-matrix that deform, cooperating with each other, a metal tube of normally circular section. The machine in question does not require, for the operation thereof, a core inside the tube to be deformed. The matrix has a circular groove adapted for the half section of the tube to be deformed and can rotate (the pre-selected rotation angle) around its vertical rotation axle, while the counter-matrix is mounted such that it can slightly oscillate around its rotation axle, in an idle manner, accompanying the tube during its deformation.

Specifically, the tube-bending machine 1 has a base or frame 2 and an upper surface 3 respectively visible in the plan views. On the upper surface 3, all the mechanisms are mounted that are necessary for bending the small-diameter metal tube 4 p, and large-diameter metal tube 4 g, respectively, both to the right and to the left. With the term “bending to the right” it is intended that, with respect to the direction of the arrow F (FIG. 1) for introduction of the tube 4 p into the machine tool 1, such tube 4.p is curved to the right (observing in top plan view as in FIG. 1); the term “bending to the left” in the case of the small tube (or large tube) is interpreted in an analogous manner. The fact that the small tube 4 p or large tube 4 g, respectively, is “bent to the right”, or better yet must be “curved to the right”, in the configuration of the machine tool 1 shown in FIGS. 1, 2 and in FIGS. 5, 6, respectively, is indicated by the symbol “R” (indicating “right”) which appears both on the counter-matrix and on the matrix which are momentarily in contact with the tube to be machined. Observing instead FIGS. 3, 4 and FIGS. 7, 8, respectively, it is observed that the metal tube 4 g and 4 p, respectively, in these figures is “curved to the left”, and this is indicated by the symbols “L” (indicating “left”) that appear on the matrix and on the counter-matrix which in these figures are in contact with the tube to be machined. Therefore, as will also be clarified hereinbelow, in each position or configuration of the machine, the operator will never err regarding the mode to use the system.

That said, before entering into the heart of the description of the part characterizing the present invention—i.e. the means that allow the above (briefly) described operation of the machine tool 1, it is recalled that the machine 1 has a system (per se known) for moving the counter-matrix closer to the matrix, which substantially comprises a screw and a hand-wheel. The screw is indicated by the reference number 5 and is situated inside a longitudinal opening 6 of the upper surface 3 of the machine. The hand-wheel 9 is rotated in order to rotate the ball screw 5, which in this case moves closer or away (based on the rotation sense of the hand-wheel 9) to/from movable block 7, which thus translates along the lateral guides 8, 8′ of the longitudinal opening 6. On said movable block 7, the counter-matrix is in turn mounted respectively for small tubes and for large tubes, in the manner that will be described hereinbelow.

Now, entering into the heart of the invention, the matrix can be of the type for bending small tubes 4 p, and in this case it is indicated in the figures by reference number 10 p, or of the type for bending large tubes 4 g, and in this case it is indicated in the figures by the reference number 10 g. In other words, according to whether it is desired to bend large tubes or small tubes, a different matrix (10 g or 10 p) is mounted on the axle 11 arranged on the side longitudinally opposite the upper surface 3 with respect to the hand-wheel 9 for adjusting the position of the movable block 7, which translates along the guides 8, 8′ that are parallel to each other of the longitudinal opening 6 of the upper surface 3.

In reality, according to the present invention, the shaft 11 only serves for centering, but there is an adapter (with which the shaft 11 is integral) that is insertable in an element with quadrangular recess (not shown), present on the surface and hidden in the figures by the matrix (and by the same adapter), constituting the power take-off of the gear motor system and used for rotating the matrix 10. The adapter has two very strong/thick drive teeth, on its upper side, which transmit the motion to the lower base (not shown) of the matrix (10 p or 10 p), while the lower base or side of the adapter (arranged between the matrix and the aforesaid power take-off) bears a protuberance complementary to said power take-off (quadrangular recess) and is insertable in/on the latter. The adapter thus constitutes an intermediate element of variable shape only on the upper part, to be arranged between said power take-off and the pre-existing (large or small) matrix. The drive teeth on the upper part of the adapter must be sufficiently strong to resist the stress of the particular tube to be deformed and hence they have thickness that suitably varies based on the matrix to be mounted above the adapter, which has on the lower part, for example, suitable cavities complementary to the drive teeth of the adapter. Other embodiments of the adapter and of the form of the power take-off are of course possible.

That said, the present invention essentially consists of the fact of having conceived a “double-twist” system, i.e. with double rotation (see the description hereinbelow), which allows adapting a single machine to both right and left bending of small and large diameter tubes, where with “small” and “large” it is intended a range of thicknesses and diameters, and particularly the maximum sizes. In other words, given a maximum power that the machine is capable of developing, said machine can be adapted to a range of diameters and thicknesses of the tube, which range from a pre-established minimum value up to a pre-established maximum value allowed by the power provided by the machine.

Specifically, the double-twist system of the present invention comprises a member of “double-twist” type, i.e. with double rotation, formed by a metal block 13 with double rotation, removably mounted/inserted from above on a vertical central axle 12 of the underlying movable/translatable metal block 7. Specifically, the surface of the movable/translatable block 7 is substantially flat and smooth/lapped, and it bears the vertical central axle 12 (with cylindrical form) which is integral therewith and vertically projects therefrom. The double-twist block 13 has a central hole which allows receiving the vertical pin 12 of cylindrical form, while on the side a lever arm, or rotation arm 14, projects from a flat lateral surface 24 of the double-twist block 13 in a direction preferably perpendicular to said lateral surface, also being integral with such lateral surface 24.

Continuing in the description of the double-rotation block 13, it comprises—on both of its opposite shorter sides (which in plan view have a rounded-tip shape)—a seat/recess that receives a respective rotatable arm 15 p and 15 g in rotation (it is observed that, in order to avoid excessive complication in FIG. 1, some numbers are reported in the following figures). Each rotatable arm 15 p/15 g rotatably and removably supports, by means of the corresponding removable vertical pin 18 p (or 18 g), a counter-matrix for bending small tubes (and large tubes, respectively); the counter-matrix is of the type known from a patent application—by the same Applicant—already mentioned above, i.e. RM2012A000620. Specifically, the counter-matrix mounted on the respective rotatable or oscillating arm 15 p,g comprises a roller 16 p,g and an insert 17 p,g (the latter made of very hard, anti-friction and wear-resistant material) with semi-cylindrical and ovaled active surface (as described in the abovementioned patent) that comes into grazing contact with the tube 4 p,g to be bent. The arm 15 g can comprise different circular holes for the insertion, in variable positions of the rotation pin, of the introduction roller 16 g, which, like the roller 16 p, clearly has a groove with substantially semi-circular section adapted for the section of the respective tube to be bent. With regard to all the details of the counter-matrix (16 p, 17 p) and (16 g, 17 g), respectively, full reference is made to the abovementioned prior patent application RM2012A000620, which is considered herein to be entirely included/incorporated in the present description for any technical detail. Of course, in the present application, there are however two counter-matrices of this type already described in the prior application, in which the indications “p” and “g” of course refer to “small” and “large” i.e. to the machining of a small or large metal tube (see above).

The introduction rollers 16 p,g are rotatably mounted on the arm 15 p,g while the inserts are removably mounted in order to easily substitute them if worn. The size of the rollers and inserts is adapted to that of the tube to be bent. The machine can be provided with a respective kit (arm, insert, roller, matrix) for a given form of the tube 4 to be bent, which can be immediately mounted in its entirety on the machine and on the respective end (with rounded-tip shape) of the double-rotation block 13.

In order to understand the present invention, it is necessary to describe the operation of the machine with reference to all eight of the figures enclosed with the present patent application.

First of all, it is necessary to indicate that the block 13 is termed “double rotation” since it is made to rotate 180° around its vertical axle 12—in the horizontal plane (plane of the figure)—by driving the lever 14, as is evident from the comparison between FIGS. 1 and 3, for example, which is made to rotate around a “horizontal axle”, i.e. extracted from the central vertical cylindrical pin 12 and re-inserted in the latter in an overturned manner, as is evident from the comparison between FIGS. 1 and 7, for example.

By examining FIG. 1, it is seen that the matrix 10 p has been mounted on the above-described adapter (which remains hidden by the same matrix 10 p in FIG. 1 and is interposed between the power take-off of the machine and the matrix 10 p), and the position of the block 13 has then been adjusted with regard to the optimal distance between the matrix 10 p and the counter-matrix (16 p, 17 p). During operation, as is visible in FIG. 2, the tube 4 p is bent to the right (with respect to the introduction direction F of FIG. 1), as also indicated by the symbols “R” incised on the metal of the counter-matrix 10 p (as well as of the relative drive bracket 19 p of the tube 4 p), of the arm 15 p, and close to the corresponding rounded-tip end of the double-twist block 13. Analogous observations are valid for the other figures and will not be repeated herein. During the rotation of the matrix 10 p and the cold deformation/bending of the tube 4 p, the arm 15 p accompanies (slightly rotating) the movement of the tube, as already generally known by the man skilled in the art.

In order to bend a large tube 4 g to the left, one operates the lever 14 and rotates it from the first initial position (that of FIG. 1), by 180°, to the initial position shown in FIG. 3 (second initial position of the block 13), and by mounting the matrix 10 g on the shaft 11 and suitably adjusting, by means of the hand-wheel 9, the relative distance between matrix 10 g and counter-matrix (16 g, 17 g) one proceeds with the bending to the left of a large tube 4 g (FIG. 4). It is observed that the bracket 19 g is rotatable 90° in a manner so as to make the writing (incision in the metal) “L” appear and to cover the writing (incision) “R” (see instead FIG. 5). Then, one proceeds to bend the tube in the conventional manner.

In order to bend a large tube 4 g to the right, (see FIGS. 3 and 5), the block 13 is overturned 180° (third initial position, starting from its second initial position shown in FIG. 3), while the matrix 10 g is previously rotated by means of the motor of the machine, around the vertical axle 11, until it reaches the starting position shown in FIG. 5 (see also the reference arrow 20 on the matrix 10 g; this establishes the two virtual zeroes of the machine, according to FIGS. 1 and 5 and FIGS. 3 and 7, respectively, the matrix automatically being moved towards the respective zero according to whether one must bend to the right or to the left, respectively, hence it is not necessary to overturn it as occurred in the prior art). It is observed that the bracket 19 g is rotated 90° so as to make the writing (incision in the metal) “R” appear and to cover the writing (incision) “L” (see instead FIG. 3). Then, one proceeds to bend the tube in the conventional manner.

In order to bend a small tube 4 p to the left (starting, it is assumed, from the configuration of the machine shown in FIG. 5), one rotates the lever 14 180° as described above, in the horizontal plane, reaching the fourth initial position of the block 13, represented in FIG. 7. Of course, it is also necessary to move the block 13 closer by means of the translation of the underlying block 7 on which it is mounted (see above), by using the screw 5 and the hand-wheel 9.

The above-described operation would of course not be possible without suitable abutments adapted to prevent the rotation of the double-twist block 13 during the deformation of the tube, whether small or large. This will be described hereinbelow.

FIG. 5 is considered presently. The zones indicated by the reference number 21 on the block 13 are recessed (i.e. they are situated on a lower ideal or level horizontal plane) with respect to the plane (also ideal) defined by the raised regions 23. The recessed zones 21 and the raised zones 23 are separated from each other by a vertical wall which, in plan view, assumes the form of a curve 22 with respectively curved and rectilinear sections. Analogously (see FIG. 4), the other side of the block 13 has corresponding recessed zones or raised regions, as well as a corresponding demarcation line (in reality, a vertical wall), which in FIG. 4 are indicated with reference numbers 21′, 23′, 22′. By observing FIG. 6, it is noted that the tube 4 g (being deformed) would tend to rotate the block 13 in counter-clockwise sense around the central vertical pin 12 for rotation of the block 13 on the block 7 (by rotation of the block 13 on the block 7, it is only intended the rotation caused before the machining by means of the lever 14, since during the machining of the metal tube the block 13 is of course immobile). In order to oppose such counter-clockwise rotation of the block 13 around the vertical axle 12 which is integral with the underlying translation block 7, a projection of parallelepiped form also projects from the upper surface of the translatable block 7; such parallelepiped projection is not visible in any of the figures of the present document since it remains hidden by the double-twist block 13. Said parallelepiped projection integral with the underlying translatable block 7 is centrally arranged in proximity to the short side of the block 7 (which in plan view forms a rectangle), between said short side and the axle 12 integral with the block 7. Said parallelepiped projection, being in contact (in FIG. 6) with the abutment 22′ of FIG. 4 (where the incision “R” appears), prevents the counter-clockwise rotation of the block 13 in the operating condition of FIG. 6. Analogous considerations are valid for the other operating conditions. In practice, the vertical walls 22, 22′ act as abutment in order to prevent the rotation of the block 13 during the tube bending operation (whether the tube is small or large). Hence, the form of the respectively “upper” and “lower” surface of the block 13 is such to allow the rotation of the block 13 by means of the lever 14, in order to attain a machining position, but such to prevent the rotation of the same block 13 during machining.

In simple terms, if it is desired to bend a same-size tube first to the right and then to the left, or vice versa, it is first necessary to overturn the double-twist block 13, while if it is instead desired to pass from a larger tube to a smaller tube, or vice versa, it is necessary to rotate said block 13 in the horizontal plane (by means of the lever 14).

The machine, provided with a plurality of kits (matrix and counter-matrix, i.e. with insert and roller, with sizes variable over a wide spectrum of values), is capable of meeting all the possible requirements, bending tubes both to the right and to the left, starting from a size of for example 0.8 centimeters diameter up to 7.6 centimeters and beyond. Only the strength of the kit components changes; such components are interchangeable on the machine, as was described above. The materials are for example cemented steel for the insert 17 g/17 p, or amco, i.e. anti-friction and wear-resistant materials.

The man skilled in the art could make obvious modifications of the abovementioned preferred embodiments. For example, the counter-matrix could be substituted by other counter-matrices of the prior art, formed by a single piece. Another obvious modification could consist of making one of the two arms of the “pivot” 13, i.e. of the double-rotation block 13 which can rotate around the cylindrical pin 12 of the translatable block 7, longer than the other arm. Then, with this variant, it is possible to reduce the translation movements of the translatable block 7 (by means of the hand-wheel 9), in the passage from the machining of a large tube ad a small tube and vice versa. It is also observed that the anti-rotation means, adapted to prevent the rotation of the overturnable pivot 13 during the machining/deformation of the tube or section bar, can in reality also be made different from simple abutments. For example, these could consist of movable teeth (fitting means), mounted on the surface, which are selectively engaged in/with corresponding cavities of the member 13, selectively preventing the rotation thereof.

The present invention can thus be obtained in multiple forms, without departing from a single inventive concept. The inventive concept is that of having available a machine of specific or predetermined power, and hence also with specific characteristics (size, strength, etc.) of its components (screw 5, hand-wheel 9, slide block 7, double-rotation block 13), a series of variable kits for adapting a particular tube to be machined, where with “kit” it is intended: the matrix (including its pin and drive bracket of the tube), the counter-matrix (roller, insert), the oscillating arm of the counter-matrix. The present discussion was up to now centered on tubes with circular section. Of course, the invention is however also applicable to tubes/profiles/bars with any section, oval, rectangular, square, possibly also made of solid material (this depends on the strength of the material). In accordance with the section of the tube/section/bar to be bent, also the kit (matrix with groove of corresponding form, counter-matrix with suitably-modified roller and insert) will be varied. In addition, as already stated above, the invention is also applicable to a kit which comprises a counter-matrix formed by a single piece, i.e. of type already known for some time. As an example, while up to now it was possible to bend small-medium tubes with round section, from 40 mm up to 48 mm (diameter), with one machine, and medium-large tubes of 60 mm to 76 mm (diameter), with a second machine, depending on the power that can be developed by the machine, now, according to the invention, once the maximum available power is set (which depends on the machine type), tubes can be bent that range from 76 mm to 40 mm and even less, or (if the power of the machine is only “60 mm”, i.e. if it only allows bending tubes only up to 60 mm), then with only one machine it is possible to bend metal tubes with round section starting from 60 mm to 40 mm and even less, always including all the intermediate values of the tube diameter, simply by changing the kits and rotating the block or “pivot” 13. It is observed that a more powerful machine, in bending smaller tubes, will use less power; nevertheless, it will be capable of doing this due to the present invention.

The present tube-bending machine can preferably have, in the base 2, suitable recesses which allow transporting it by means of the clamps of a fork lift, as well as, on another side (narrower side), other openings (this time lacking bottom) for the transport by means of the strips (with wheels) of a pallet-carrier carriage with wheels rested on the ground. The positions (on the base 2) of the recesses for the clamps of the fork lift are selected in a manner such to appear offset with respect to the geometric center of the machine body, and such to appear centered with respect to the center of gravity of the machine itself.

LIST OF THE REFERENCE SYMBOLS

-   1 machine for bending (metal) tubes -   2 base -   3 upper surface -   4 p small-diameter tube/profile -   4 g large-diameter tube/profile -   5 adjustment screw for the position of 13 -   6 longitudinal opening of the surface 5 -   7 translation block -   8, 8′ longitudinal guides of 7 -   9 hand-wheel -   10 p matrix for small tubes/profiles -   10 g matrix for large tubes/profiles -   11 shaft of the adapter (useful for centering matrix) -   12 vertical shaft/axle integral with 7 -   13 “double-twist” block -   14 rotation lever for 13 -   15 p (small) counter-matrix arm -   15 g (large) counter-matrix arm -   16 p (small) counter-matrix roller -   16 g (large) counter-matrix roller -   17 p (small) counter-matrix insert -   17 g (large) counter-matrix insert -   18 p rotation pin of 15 p -   18 g rotation pin of 15 g -   19 p bracket of 10 p -   19 g bracket of 10 g -   20 virtual zero position indicator -   21 recessed zone -   21′ recessed zone -   22 vertical abutment surface (anti-rotation means) -   22′ vertical abutment surface (anti-rotation means) -   23 elevated/raised region -   23′ elevated/raised region 

1. Machine (1) for bending a piece having longitudinal form such as a tube or a section bar, e.g. with circular, rectangular, oval section or the like, comprising a base (2) with an upper surface (3), as well as power means, for developing the power and the mechanical torque necessary for bending said piece to be bent, such as a gear motor, or the like, in which said power means transmit the rotary motion to a matrix (10 p; 10 g) mounted on the upper surface (3) and having substantially circular form with an annular groove whose profile substantially copies the form of the transverse half section of the piece, the machine (1) further comprising a counter-matrix (16 p, 17 p; 16 g, 17 g) cooperating with said matrix (10 p; 10 g) and which is mounted in front of the matrix itself above the upper surface (3), in a manner so as to make the piece pass between the matrix and the counter-matrix during operation, the matrix (10 p; 10 g) further comprising a drive bracket (19 p; 19 g) and the piece being inserted during the operation of the machine (1) also between the drive bracket (19 p; 19 g) and the wall of the annular groove of the matrix (10 p; 10 g), wherein the machine (1) provides for a member (13) which is mounted in an unthreadable or extractible manner from a vertical axle (12) as well as rotatable around the same vertical axle (12) above the upper surface (3), said member (13) having a first side and a second side, as well as a first end and a second end, said first end of the member (13) supporting a first counter-matrix (16 p, 17 p) for bending small pieces, with smaller transverse section, and said second end of the member (13) supporting a second counter-matrix (16 g, 17 g) for bending large pieces, with greater transverse section, said first end and said second end of the member (13) being substantially aligned with respect to the center of the matrix (10 p; 10 g) as well as with respect to said vertical shaft or axle (12) during operation, and said member (13) being rotatable around the vertical axle (12) in order to selectively bring one or the other of said counter-matrices (16 p, 17 p or 16 g, 17 g) in a position such to cooperate with the respective matrix (10 p or 10 g) during the operation of the machine (1), and wherein during operation, the member (13) assumes one of the four following positions and cannot rotate by virtue of anti-rotation means: a first position, with the first side of the member (13) directed upward, in which the first counter-matrix (16 p, 17 p) cooperates with a first matrix (10 p), for small pieces, bending a small piece (4 p) to the right; a second position, rotated 180° with respect to the first position around the vertical axle (12) and in which the second counter-matrix (16 g, 17 g) cooperates with a second matrix (10 g), for large pieces, bending a large piece (4 g) to the left; a third position, with the first side of the member (13) directed downward, in which the second counter-matrix (16 g, 17 g) cooperates with said second matrix (10 g), for large pieces, bending a large piece (4 g) to the right; and a fourth position, rotated 180° with respect to the third position around the vertical axle (12) and in which the first counter-matrix (16 p, 17 p) cooperates with said first matrix (10 p), for small pieces, bending a small piece (4 p) to the left.
 2. Machine (1) according to claim 1, wherein said member (13) is mounted on a block that can be translated (7) in the direction defined by said first and said second end when said ends are aligned with said center of the matrix (10 p; 10 g), said vertical axle (12) being integral and perpendicular to an upper surface (7) of the translatable block.
 3. Machine (1) according to claim 2, wherein the position of the translatable block (7) is adjustable by means of guide and regulation means (5, 6, 8, 8′, 9), for moving the first counter-matrix (16 p, 17 p) closer to/away from the first matrix (10 p), or respectively the second counter-matrix (16 g, 17 g) closer to/away from the second matrix (10 g).
 4. Machine (1) according to claim 2, wherein said anti-rotation means are vertical abutment surfaces (22, 22′) formed respectively on the first side and on the second side of the member (13), which cooperate with a fixed projection, and in particular with a projection integral with the upper surface of the translatable block (7).
 5. Machine (1) according to claim 1, wherein an adapter is provided for adapting a power take-off of said power means to any one matrix (10 p, 10 g) for large pieces (4 g) or small pieces (4 p).
 6. Machine (1) according to claim 1, wherein the first and the second counter-matrix, respectively mounted on the first and second end of the member (13), constitute counter-matrices comprising an arm (15 p; 15 g) rotatably mounted on the respective end of the member (13), and further comprising, on said arm (15 p; 15 g), a roller (16 p, 16 g) and an insert (17 p, 17 g) made of hard, anti-friction and wear-resistant material, e.g. cemented steel or amco, arranged at the opposite end of the arm with respect to the roller (16 p, 16 g).
 7. Machine (1) according to claim 1, wherein said member (13) has a lever arm (14) in order to make it rotate from said first position thereof up to said second position thereof, as well as from said third position thereof up to said fourth position thereof.
 8. Machine (1) according to claim 1, wherein said drive bracket (19 p; 19 g) mounted on the matrix (10 p; 10 g), is rotatable 90° between a first position for bending tubes to the right, and a second position, for bending tubes to the left.
 9. Machine (1) according to claim 1, wherein the matrix, including its pin and its drive bracket of the piece or tube, the counter-matrix comprising the roller, the insert and the relative oscillating arm of the counter-matrix, form a kit with variable characteristics, including size and/or strength, mountable on the machine as a function of the size, thickness of the material and the material of the piece to be bent.
 10. Machine (1) according to claim 1, wherein its base (2) has on the lower part, on a longer side thereof, two recesses in which clamps of a fork lift are inserted, as well as on another side thereof, narrower, openings lacking bottom for the insertion of strips with wheels belonging to a manual pallet-carrier carriage with wheels restable on the ground, wherein the positions on the base (2) of the recesses for the clamps of the fork lift are selected in a manner such to be centered with respect to the center of gravity of the machine (1) itself.
 11. Machine (1) according to claim 1, wherein said member (13) is configured in a manner so as to support at said first end, in a removable manner and selectively or alternatively, various counter-matrices that form the components of a kit of counter-matrices, for different types of pieces (4 p) with smaller size, and in a manner so as to support at said second end, in a removable manner and selectively or alternatively, various counter-matrices that form the components of a kit of counter-matrices, for different types of pieces (4 g) with larger size, compatibly with the maximum power and mechanical torque that can be developed by the machine (1).
 12. Machine (1) according to claim 5, wherein said adapter is configured in a manner so as to adapt the power take-off of said power means to any one pre-existing matrix, constituting part of a kit of matrices substitutable for pieces with smaller size up to the maximum size compatible with the operation of the machine, i.e. with its maximum power and maximum mechanical torque.
 13. Machine (1) according to claim 1, wherein it provides for a system of automatic control and two distinct virtual zero points, that is of reference for a respective initial starting portion of the matrix for bending the piece respectively to the right and to the left, from which the machine starts to bend the tube respectively to the right and to the left, and wherein, based on a selective command given by an operator, the automatic control system rotates the matrix up to the virtual zero point pre-selected for bending the piece respectively to the right and to the left.
 14. Machine (1) according to claim 13, wherein the two virtual zero points are visually indicated on the matrix by an arrow (20) or by another sign that is visible for the operator, and they are separated from each other by an alpha rotation angle of the matrix around its rotation axle (11).
 15. Machine (1) according to claim 3, wherein said anti-rotation means are vertical abutment surfaces (22, 22′) formed respectively on the first side and on the second side of the member (13), which cooperate with a fixed projection, and in particular with a projection integral with the upper surface of the translatable block (7).
 16. Machine (1) according to claim 2, wherein an adapter is provided for adapting a power take-off of said power means to any one matrix (10 p, 10 g) for large pieces (4 g) or small pieces (4 p).
 17. Machine (1) according to claim 3, wherein an adapter is provided for adapting a power take-off of said power means to any one matrix (10 p, 10 g) for large pieces (4 g) or small pieces (4 p).
 18. Machine (1) according to claim 4, wherein an adapter is provided for adapting a power take-off of said power means to any one matrix (10 p, 10 g) for large pieces (4 g) or small pieces (4 p).
 19. Machine (1) according to claim 2, wherein the first and the second counter-matrix, respectively mounted on the first and second end of the member (13), constitute counter-matrices comprising an arm (15 p; 15 g) rotatably mounted on the respective end of the member (13), and further comprising, on said arm (15 p; 15 g), a roller (16 p, 16 g) and an insert (17 p, 17 g) made of hard, anti-friction and wear-resistant material, e.g. cemented steel or amco, arranged at the opposite end of the arm with respect to the roller (16 p, 16 g).
 20. Machine (1) according to claim 14, wherein alpha=90°. 